Durst La 1200, CLS450 head, too bright!

[ChrisN]

Today I've finally got my darkroom finished to the point where I can start to use it, and I fired up the Durst Lab 1200 for the first time since acquiring it some time ago. It has a CLS 450 head with Femobox 450. I'm using it to print 4x5 B&W negs, at 8x10 on Ilford RC multigrade paper. My problem is that even with filtration dialed in for grade 3 1/2 and the lens closed down to f/22 my exposure time is only 10 seconds. I'd prefer to use an exposure in the 20 to 30 second range and at f/8.

I suspect I might be missing a diffuser in the Femobox. There is a diffuser in the base of the head, and one in the base of the Femobox, but none in the top of the Femobox. Any ideas? Thanks!

[Tony Lakin]

Today I've finally got my darkroom finished to the point where I can start to use it, and I fired up the Durst Lab 1200 for the first time since acquiring it some time ago. It has a CLS 450 head with Femobox 450. I'm using it to print 4x5 B&W negs, at 8x10 on Ilford RC multigrade paper. My problem is that even with filtration dialed in for grade 3 1/2 and the lens closed down to f/22 my exposure time is only 10 seconds. I'd prefer to use an exposure in the 20 to 30 second range and at f/8.

I suspect I might be missing a diffuser in the Femobox. There is a diffuser in the base of the head, and one in the base of the Femobox, but none in the top of the Femobox. Any ideas? Thanks!

Hi
I have a Laborator 1000CE with a CLS450 head and Taunobox 450 5X4 mixing chamber, the Taunobox has a Diffuser on top as well as on the bottom I suspect your Femobox should have a top diffuser also, it should be a simple matter for you to place a piece of diffusing material on top ie opal acryllic, ground glass or even a piece of 5x4 film processed to a suitable density.

Ihope this helps.
Good luck.

[Roger Thoms]

Here is a listing on the auction site for a Durst diffusion panel. item # 150411616679

Roger

[ic-racer]

Here is a listing on the auction site for a Durst diffusion panel. item # 150411616679

Roger

That is the thin bottom one. Maybe that is what the OP has and he needs to find the thicker one.

[Tony Lakin]

Today I've finally got my darkroom finished to the point where I can start to use it, and I fired up the Durst Lab 1200 for the first time since acquiring it some time ago. It has a CLS 450 head with Femobox 450. I'm using it to print 4x5 B&W negs, at 8x10 on Ilford RC multigrade paper. My problem is that even with filtration dialed in for grade 3 1/2 and the lens closed down to f/22 my exposure time is only 10 seconds. I'd prefer to use an exposure in the 20 to 30 second range and at f/8.

I suspect I might be missing a diffuser in the Femobox. There is a diffuser in the base of the head, and one in the base of the Femobox, but none in the top of the Femobox. Any ideas? Thanks!

Hi again
Had another thought, if you are happy with the evenness of the illumination and only using the L1200 for Multigrade printing you can use the Cyan filter to create neutral density this would not affect the contrast, if you used graded papers you could use any of the filters as neutral density.

[athens01]

I'm not familiar with that enlarger, but many have a high and a low light setting. Like the above post, (and if it has a color head), dialing in equal parts of cyan magenta and yellow will add neutral filtration, so 25 cyan, 75 yellow and 40 magenta is the same filtration as 0 cyan, 50 yellow and 20 magenta. When I print color, I try and print at the same f/stop and exposure time and just adjust color and maintain the same exposure by changing filtration.

[athens01]

Apologies for my math: 25c, 75y, 40m = 0c, 50y, and 15m. Or for that matter 100c, 175y , 140m in filtration. You could also use actual ND filters but...


Maybe my math explains so of those inconsistent prints.

[ic-racer]

Cyan has no effect. It cuts light that the paper can't 'see.'

If you need more 'neutral density' add extra Y and M together.

[Tony Lakin]

Cyan has no effect. It cuts light that the paper can't 'see.'

If you need more 'neutral density' add extra Y and M together.

I stand to be corrected but I am sure that adding cyan filtration must reduce the amount of light reaching the negative regardless of the sensitivity of the paper.

[athens01]

Like I said, I've only used cyan to manage exposure time in color printing, try it an let us know if adding 100 points (for example) of cyan doesn't change exposure time. I'm also surprised there's no variable output on the enlarger.
I guess having a stack of standard ND filters on hand is the easiest unless, of course, the paper doesn't want to see the red/cyan filtered by those either.